Merge pull request ipfs/go-unixfsnode#26 from ipfs/partial-file-test

Partial file test

This commit was moved from ipfs/go-unixfsnode@3629b1b

Author: hannahhoward

unixfs/node/test/doc.go

@@ -0,0 +1,4 @@
+// Package test provides ADL testing of the ipld specification around
+// * traversal making use of match subsets
+// * largeByteNode readers
+package test

unixfs/node/test/partial_file_access_test.go

@@ -0,0 +1,108 @@
+package test
+
+import (
+	"bytes"
+	"context"
+	"io"
+	"testing"
+
+	u "github.com/ipfs/go-ipfs-util"
+	"github.com/ipfs/go-unixfsnode/data/builder"
+	"github.com/ipfs/go-unixfsnode/file"
+	dagpb "github.com/ipld/go-codec-dagpb"
+	"github.com/ipld/go-ipld-prime"
+	"github.com/ipld/go-ipld-prime/datamodel"
+	"github.com/ipld/go-ipld-prime/linking"
+	cidlink "github.com/ipld/go-ipld-prime/linking/cid"
+	basicnode "github.com/ipld/go-ipld-prime/node/basic"
+	"github.com/ipld/go-ipld-prime/traversal"
+	sb "github.com/ipld/go-ipld-prime/traversal/selector/builder"
+)
+
+func TestPartialFileAccess(t *testing.T) {
+	buf := make([]byte, 10*1024*1024)
+	u.NewSeededRand(0xdeadbeef).Read(buf)
+	r := bytes.NewReader(buf)
+
+	ls := cidlink.DefaultLinkSystem()
+	storage := cidlink.Memory{}
+	ls.StorageReadOpener = storage.OpenRead
+	ls.StorageWriteOpener = storage.OpenWrite
+
+	f, _, err := builder.BuildUnixFSFile(r, "", &ls)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// get back the root node substrate from the link at the top of the builder.
+	fr, err := ls.Load(ipld.LinkContext{}, f, dagpb.Type.PBNode)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	ufn, err := file.NewUnixFSFile(context.Background(), fr, &ls)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	openedLinks := []ipld.Link{}
+	ls.StorageReadOpener = func(lc linking.LinkContext, l datamodel.Link) (io.Reader, error) {
+		openedLinks = append(openedLinks, l)
+		return storage.OpenRead(lc, l)
+	}
+
+	// read back out the file.
+	out, err := ufn.AsBytes()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !bytes.Equal(out, buf) {
+		t.Fatal("Not equal")
+	}
+
+	fullLen := len(openedLinks)
+
+	openedLinks = []ipld.Link{}
+
+	partial, err := ufn.(datamodel.LargeBytesNode).AsLargeBytes()
+	if err != nil {
+		t.Fatal(err)
+	}
+	half := make([]byte, len(buf)/2)
+	if _, err := partial.Read(half); err != nil {
+		t.Fatal(err)
+	}
+	if len(openedLinks) >= fullLen {
+		t.Fatal("should not have accessed full file on a partial read.")
+	}
+
+	openedLinks = []ipld.Link{}
+
+	prog := traversal.Progress{
+		Cfg: &traversal.Config{
+			LinkSystem: ls,
+		},
+	}
+	sb := sb.NewSelectorSpecBuilder(basicnode.Prototype.Any)
+	ss := sb.MatcherSubset(5*1024*1024, 6*1024*1024)
+	sel, err := ss.Selector()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if err := prog.WalkMatching(ufn, sel, func(_ traversal.Progress, n datamodel.Node) error {
+		b, err := n.AsBytes()
+		if err != nil {
+			t.Fatal(err)
+		}
+		if len(b) != 1024*1024 {
+			t.Fatalf("wrong length: %d", len(b))
+		}
+		return nil
+	}); err != nil {
+		t.Fatal(err)
+	}
+	if len(openedLinks) >= fullLen {
+		t.Fatal("should not have accessed full file on a partial traversal.")
+	}
+}